Touch fastener products have a field of small hooking members, also known as fastening elements, that can engage fibers, such as loops, to hold two things together. Early male touch fastener products were formed by weaving loops of drawn filament, stabilizing the filament loops and then cutting one side of each loop to form a hook. Later, methods of molding very small male fastening elements were developed, resulting in arrays of hooking members extending from a sheet of resin. Some male fastening elements are molded to have an engageable head at the end of a molded stem. For example, J-hooks and palm-tree style hooks may be molded in closed cavities, or formed by cutting and stretching an extruded rail. Some other male fastening elements are formed by molding straight stems extending from a sheet of resin, and then deforming the ends of the stems to form heads. Fastening elements with heads that overhang their stems on essentially all sides of the stem are called mushrooms or mushroom hooks. While molding hooks or precursor stems can be very cost-effective, there are practical limits to the shapes and sizes of features that can be readily molded at high speeds.